Thyrotropin glycosylation has been characterized during pulse-chase labeling using newly developed methods of high performance liquid chromatography. Inhibitors of glucosidase block TSH carbohydrate processing at different steps yielding abnormally glycosylated TSH forms whose functional characteristics are being investigated. Thyroid hormone and thyrotropin-releasing hormone differentially regulate thyrotropin apoprotein and carbohydrate biosynthesis. Apoprotein biosynthesis is primarily regulated in the free Beta subunit while carbohydrate biosynthesis is primarily modulated in the combined Alpha subunit.